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Mold Growth on Window Sills: Causes and Prevention

The presence of mold on window sills can cause many problems, including stains and compromised window life span. It can also trigger allergies and other respiratory illnesses. In this blog, local window and door replacement company  Renewal by Andersen® of Southwest Missouri shares a look at the things that you can do to prevent mold growth on window sills.Mold Growth on Window Sills: Causes and Prevention
What Causes Mold Growth on Window Sills?

High moisture levels are conducive to mold growth, which is why it thrives in humid areas such as basements, bathrooms, and attics. Moisture that comes from indoor condensation and humid outside air usually collect at the window sill, and doesn’t immediately dry out.

Exposed wood may also absorb and retain moisture. Sometimes these areas are blocked by window treatments, which would then allow mold to grow undisturbed and hidden from view. Certain types of mold, particularly black mold, are notoriously difficult to remove, even on the best vinyl replacement windows on the market.

The Effects of Mold

We have mentioned how the presence of mold can affect the respiratory system in both children and adults. To elaborate, some people have sensitivity to mold spores, and may develop stuffy nose, coughing, and throat irritation when exposed to high levels mold spores in the air. Skin and eye irritation may accompany these symptoms. Certain types of allergies may also be triggered by mold. A 2004 study conducted by the Institute of Medicine presents evidence that links exposure to mold indoors with asthma, hypersensitivity pneumonitis, and other upper respiratory problems.

How to Prevent Mold Growth on Window Sills

While you can’t completely eliminate mold spores from getting into your home, there are some things that you can do to prevent mold growth on window sills, as well as in other parts of your home:

Maintain Relative Indoor Humidity — Humidity levels change depending on the season: it’s dry during winter and humid during summer. A home humidifier/dehumidifier helps maintain indoor humidity relative to outdoor levels by releasing or absorbing moisture as needed, preventing window condensation and other issues that can lead to mold growth.

Allow Regular Ventilation — Opening your windows for at least 15 minutes a day helps flush out indoor air pollutants, including mold spores. You should also make sure that the air filters in your home ventilation system are replaced when full.

Regularly Clean Your Windows — Make it a point to clean your windows twice a year. Low-maintenance windows with easy cleaning features such as removable or tiltable sashes make this task easier and safer. Make sure that the window treatments are likewise cleaned.

Renewal by Andersen of Southwest Missouri is your leading provider of popular window styles, including double hung replacement windows. Give us a call at (417) 268-9301 or fill out our contact form to schedule an appointment.


"I've been impressed with each step so far. Josh my salesman, Gerry my project manager & the installation crew have all been great people to work with. Also, the many different office workers who have reached out to let me know how things were progressing are greatly appreciated. Thank you to all team members!"

J Nick
Nov 15, 2022

"They did a super job, matched my woodwork stain perfectly, cleaned up well after their work was done and were polite and professional."

alana mccleary
Nov 15, 2022

"From initial review and purchase to installation, this team provided outstanding service. We were informed about the project status from start to finish. Everything was clear to us. We were very please the 6 windows were ready and installed earlier than originally planned. We'll work with them again on our next window replacement project."

Jeffery Brown
Nov 17, 2022

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